AC Blowing HOT, Not Just Warm

C

CountryBoy

Veteran Member
Joined
Feb 7, 2001
Location
Strasburg, VA, USA
TDI
2009 VW Jetta SportWagen TDI DSG, 2002 Jetta GLS TDI 5-Speed
Was in the jetta coming home today. Put windows up, hit AC switched and turned fan speed to two. Was starting to cool a bit and then it suddenly got very hot. The air is not just coming out warm its coming out HOT like the heat is on. Temp dial is all the way to cold. Compressor still working, I can feel it kick on. Coolant is fine, engine temp is steady. Any ideas?
 
Harvieux

Harvieux

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Aug 15, 1998
Location
Whittier,CA-USA
TDI
06 A5 Pkg.2 w/navi & ASEP
Possibly the changeover valve on the firewall on the coolant reservoir side if it's an A4 you are referring to. The change out will result in loss of freon and if you could release the exsisting freon slow enough to prevent the oil from escaping you won't have to add oil to the system. You could then replace this changeover valve and then add two 12 oz cans of R-134 totaling approx 672 grams and should be good to go even though the system calls for 750 grams. You should be sure and do this process as quickly as possible to prevent contamination from entering the a/c system while opened up. Later!
 
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mavapa

Veteran Member
Joined
Aug 29, 2000
Location
rome, ga
TDI
2001 golf
Could the heater control not be working, so that the control is turned to "cold" but it's actually set on "hot"? Also, the temperature gauge works more like an idiot light than an analog gauge. I guess if it gets really hot it will move, but mine goes to the normal position and then stays, no matter what's happening to the outside air, the AC, the engine speed or the slope of the highway. Real informative.
 
PDJetta

PDJetta

Top Post Dawg
Joined
Nov 6, 2003
Location
Northern Virginia
TDI
'04 Jetta GLS TDI Pumpe Duce Platinum Grey w/ Leather
A way to check if the heater core is putting heat into the car is to gently pinch off one of the heater hoses (wrap in cloth and use vice grips) and see if the outlet air temperature drops. From what I understand, there is no heater valve and the temperature is controled by a blend door that controls air flow to or from the heater core.

--Nate
 
C

CountryBoy

Veteran Member
Joined
Feb 7, 2001
Location
Strasburg, VA, USA
TDI
2009 VW Jetta SportWagen TDI DSG, 2002 Jetta GLS TDI 5-Speed
Possibly the changeover valve on the firewall on the coolant reservoir side if it's an A4 you are referring to. The change out will result in loss of freon and if you could release the exsisting freon slow enough to prevent the oil from escaping you won't have to add oil to the system. You could then replace this changeover valve and then add two 12 oz cans of R-134 totaling approx 672 grams and should be good to go even though the system calls for 750 grams. You should be sure and do this process as quickly as possible to prevent contamination from entering the a/c system while opened up. Later!
Click to expand...
Well I can't open the hood presently as I got into a fender bender a week back and the latch is mashed. Not schedule to be repaired until Sept. 15th.
 
C

CountryBoy

Veteran Member
Joined
Feb 7, 2001
Location
Strasburg, VA, USA
TDI
2009 VW Jetta SportWagen TDI DSG, 2002 Jetta GLS TDI 5-Speed
A way to check if the heater core is putting heat into the car is to gently pinch off one of the heater hoses (wrap in cloth and use vice grips) and see if the outlet air temperature drops. From what I understand, there is no heater valve and the temperature is controled by a blend door that controls air flow to or from the heater core.

--Nate
Click to expand...
Going by what you say nate is it possible the blend door is malfunctioning and all air is going to the heater core?
 
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weedeater

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Mar 17, 2001
Location
Reston, VA
TDI
Jetta, 2001, Baltic Green
The door is connected to the temp control knob. Turn the knob and feel/listen for door movement.
 
C

CountryBoy

Veteran Member
Joined
Feb 7, 2001
Location
Strasburg, VA, USA
TDI
2009 VW Jetta SportWagen TDI DSG, 2002 Jetta GLS TDI 5-Speed
weedeater said:
The door is connected to the temp control knob. Turn the knob and feel/listen for door movement.
Click to expand...
Dredging up an old thread. The lines are fine and apparently have coolant. I do notice in the mornings if I leave it on fan speed 1 it stays cool for awhile. If I throw it to 4 I hear a *THUNK* and it gets warm. I think you may be correct in that the blend door is broken or malfunctioning. Not terribly difficult to get to though?
 
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